Re-Enable Rust-Stable CI for Rust 1.75+

Now that [async-trait](https://blog.rust-lang.org/2023/12/21/async-fn-rpit-in-traits.html) has been stabilized in [Rust 1.75.0](https://blog.rust-lang.org/2023/12/28/Rust-1.75.0.html), we can start using the stable paths in the ci again.